Leaf for books.



No. 781,935. PATENTBD FEB. 7, 1905. L. CLARK.

LEAP FOR BOOKS.

APPLIOATIOH IILBD 110mm, 190a.

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No. 781,935. Patented February 7, 1905.

UNTTED STATES PATENT EEicE.

LINCOLN CLARK, OF CHICAGO, ILLINOIS, ASSIGNOH OF 'IWVO IIIIRDS TO W.GIFFORI) JONES AND HARRY S. JONES, OF CHICAGO, ILLINOIS.

LEAF FOR BOOKS.

SPECIFICATION forming part of Letters Patent No. 781,935, dated February7, 1905.

Application filed November I4, 1903. Serial No. 181,199.

if y and varying the place of curvature by rela Be it known that I,Lrxoonx CLARK, a cititive movement of the parts of the paper to zen ofthe United States, residing at Chicago, weaken or fracture the sizingcoatingthroughin the county of Cook and State of Illinois, out the bandportion (1 defined by said dotted haveinvented a new and useful ImprovedLeaf lines. This flexing operation may be repeatfor Books. of which thefollowingis a specilied as often as necessary; but ordinarily thecation. desired result may be obtained by folding the My inventionrelates to improvements in paper to curve the same about an almost inthesized-paper sheets forming the leaves of linitesimal radius and varyingthe place of to books, and more particularly those of loosecurvatureuntil the desired area has been leaf ledger-s. treated and finallyreversing the direction of It is desirable to provide, particularly forcurvature and varying the place of curvature accmmt-lmoks, leaves whichwill tend noruntil the same area has been flexed in the mally to lieflatwise upon each other when the opposite direction. In the flexingoperation 1 books are open to present firm surfaces to the sufficientpressure is applied to bend the papen. and a common manner of formingsuch per closely upon itself, while the continuous 5 leaves is to causean area or zone of each sheet change in the place of curvature preventsthe adjacent to its binding edge to be more flexi- 1 paper from beingsharply folded or creased. ble than the other parts of the sheet. Vari-The effect of the treatment is to thoroughly 2o ous methods have beenemployed for providfracture the sizing coatings of the paper along ingthe said flexible zones or areas; but they almost infinitely close lineswithout injuring 7 all, so far as I am aware, involve treatments 5 thefiber of the paper, which commonly is of C or operations which are morelaborious or exlinen. At the same time the sizing coatings pensive thanis thought to be desirable and in are left in such a smooth and completecondithose constructions which have proven the tion as to enable thesurfaces to be written most practical heretofore tend materially to uponfreely with ink. Thus, it will be under weaken the paper alongwell-defined lines, stood, the tenacity and smoothness of the wherelrv,particularly after frequent turning treated section of the leaf areunimpaired, of the leaves, and consequent flexing along while theflexibility is increased greatly. If

30 fhoselines, theleaves tend to become too weak desired, the paper maybe bent over a wire thereat to withstand ordinary handling. or strippresenting a blunt rounded edge and 30 My object is to provide a new andimproved then drawn across the same to flex the paper method ofrendering flexible without materiwithout creasing it, while fracturingor weakally weakening areas or zones on sized-paper ening, the sizingcoatings to decrease the resheets; and my invention consists in thesilience thereof. In the flexingoperation unimethod I employ and also inthe improved formity of curvature coupled with continuity 5 leavesproduced by the said method. of change of place of curvature isdesirable In the accompanying drawings, Figure I is to avoid theproductionofcreases,which would a plan view of a loose leaf provided inaccordunduly weaken the sheet along definite lines.

4 ance with my invention; Fig. 2, an edge view Rendering the paperhighly flexible at the of the same, and Fig. 3 also an edge viewshowsection operated upon in the mannerdescribed 9 ing the leaf bent underits own weight at the does not materially change the appearance of zoneof greatest flexibility. the paper, and the desired result is attained Arepresents a sheet of calendered paper without either thickening orthinning the 45 having a binding-edge portion a. In carrypaper at saidsection. Moreover, great uniing out my invention I subject the leafbeformity of flexibility results from the imtween, for example, thedotted lines 1/ to it proved treatment, and tests have shown thatmechanical flexing operation which consists, the tearingstrength of thepaper is practically preferably, in turning the paper upon itselfunimpaired, attributable, as suggested above,

to the preservation of the fiber of the paper and the absence ofdefinite lines of weakening. As the tenacity of the paper is practicallyunimpaired, the treated section may extend from the extreme top to thebottom edge of the leaf.

In carrying out my method any kind of ledger-paper may be provided witha bending zone without regard to the thickness of the paper,unevennesses in the surface, or the state of the paper with regard todryness.

Changes within the spirit of my invention are contemplated. Hence noundue limitation should be understood from the foregoing detaileddescription.

What I regard as new, and desire to secure by Letters Patent, is

1. The method of treating sized paper to render it more flexible overalimited bending area, which consists in minutely fracturing the sizingcoating by flexing the sheet uniformly throughout a band portion onlywithout scoring or creasing, whereby the fiber of said band portion isleft uninjured, definite lines of weakness avoided therein and thesurfaces thereof preserved for writing purposes, the remainder of thepaper being left unchanged in all its qualities, for the purpose setforth.

2. The method of treating sized paper to render it more flexible over alimited bending area, which consists in minutely fracturing the sizingcoating by subjecting the leaf to a flexing operation throughout alimited area only and varying the place of curvature uniformlythroughout said area, without scoring or creasing, whereby the fiber ofthe paper at said area is left uninjured, definite lines of Weaknessthereat avoided and the surfaces thereof preserved for writing purposes,the remainder of the paper being left unchanged in all its qualities,for the purpose set forth.

.3. The method of treating sized paper to render it more flexible over alimited bending area, which consists in minutely fracturing the sizingcoating by subjecting the leaf to a flexing operation throughout alimited area only and varying the place of curvature uniformlythroughout said area, and then reversing the direction of curvature andvarying the place of curvature uniformly throughout said area, withoutcreasing or scoring, whereby the fiber of the paper at said area is leftuninjured, definite lines of weakness thereat avoided and thesurfacesthereof preserved for writing purposes, the remainder of the paper beingleft unchanged in all its qualities for the purpose set forth.

4:. As a new article of manufacture, a leaf ofsized book-paper having atransverse band portion adjacent to its binding margin with the sizingcoatings minutely fractured uniformly throughout said band portion, saidband portion retaining its fiber and surfaces practically unimpaired andpossessing greatlyincreased flexibility, the remainder of the paperretaining its original qualities, substantially as and for the purposeset forth.

5. The method of treating a leaf of sized book-paper, to provide a zoneof increased flexibility, which consists in minutely fracturing thesizing coatings by subjecting a band portion parallel with and adjacentto the binding edge of the leaf to a flexing operation and varying theplace of curvature uniformly parallel with said binding edge throughoutsaid band portion, and then reversing the direction of curvature andvarying the place of curvature uniformly throughout said band portion,whereby the fiber at said band portion is left uninjured and definitelines of Weakness avoided, the flexibility thereat increased, and thesurfaces thereof preserved for writing purposes, the remainder of theleaf being left unchanged in all its qualities, substantially as and forthe purpose set forth.

LIN ()OLN CLARK.

In presence of- WALTER N. WINBERG, F. M. VVIRTZ.

